Vacuum switch



A g- 1962 J. H. FLATT ETAL VACUUM SWITCH 2 Sheets-Sheet 1 Filed Sept. 9,1959 INVENTORS James H. Flaff y Kenneth W. Young aRmlML Their AttorneyAug. 14, 1962 J, H. FLATT ETAL 3,

VACUUM SWITCH Filed Sept. 9, 1959 2 Sheets-Sheet 2 72 INVENTORS James H.Flatt y Kenneth W. Young F I g. 4

Their Affornqy United States Patent C) 3,049,602 VACUUM SWITCH James H.Flatt and Kenneth W. Young, Anderson, Ind., assignors to General MotorsCorporation, Detroit, Mich., a corporation of Delaware Filed Sept. 9,1959, Ser. No. 838,886 7 Claims. (Cl. 20083) This invention relates toelectric switches and more particularly to fluid pressure switches thatare actuated by vacuum and the like.

One of the objects of this invention is to provide a pressure switchthat is comprised of a minimum number of parts but which is reliable anddurable in operation.

Another object of this invention is to provide a pressure switch that isformed essentially of two easily assembled parts, namely, a case orhousing assembly and a diaphragm that is snapped over a portion of thecase or housing assembly. In carrying this object forward, the case isformed from a moldable plastic material such as nylon and has anintegral tube for connection to a vacuum source and has integralattaching means that are adapted to be snapped into an aperture in amounting plate.

Still another object of this invention is to provide a pressure switchincluding a case or housing and a diaphragm fitted thereto, thediaphragm carrying a metal plate which in one embodiment of theinvention serves at times to connect fixed contacts supported by thecase and in another embodiment of this invention serves to add rigidityto the diaphragm.

A further object of this invention is to provide a pressure switchincluding a housing carrying a diaphragm, the diaphragm in turn carryinga metal contact plate which engages a pair of spaced contacts carried bythe housing and a post formed integral with the housing. In carryingthis object forward the contacts are located at the same distance fromthe at rest position of the metal plate while the end of the post islocated at a greater distance. This causes a tilting of the contactplate as it first engages the contacts and then tilts to engage the endof the post when the switch is connected with vacuum. It has been foundthat this tilting causes the plate to rotate slightly during eachactuation of the switch so that a wiping action is present and adifferent part of the contact plate is presented to the contacts duringeach actuation of the switch.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawing wherein preferred embodiments in the invention are clearlyshown.

In the drawings:

FIGURE 1 is a plan view of an electric switch made in accordance withthis invention.

FIGURE 2 is a sectional view taken along line 22 of FIGURE 1.

FIGURE 3 is a plan view of a modified electric switch made in accordancewith this invention.

FIGURE 4 is a sectional view taken along line 4-4 of FIGURE 3.

Referring now to the drawings and more particularly to FIGURES 1 and 2,it is seen that the electric switch includes a case or housing generallydesignated by reference numeral 10. This case or housing is preferablyformed from a plastic moldable material such as nylon but could beformed of any other electric insulating material. The housing has acircumferentially extending flange designated by reference numeral 12and has outwardly flared projecting teeth designated by referencenumeral 14 which are formed as sectors as is clearly ap parent fromFIGURE 1. The teeth 14 are formed integral with the housing 10 and areadapted to be forcibly inserted within an aperture in a mounting platewhereupon they snap outwardly to secure the electric switch to amounting plate. The housing 10 also has integral tubular portions 16 and18 which serve as passage means for connecting the interior of the caseor housing 10 with a Vacuum source. The tubes 16 are adapted to befitted with tubular connectors for connecting a vacuum source to theinterior of the housing 10.

The housing 10 at its interior is formed with tubular portions 20 whichreceive the rivets 22. Each rivet 22 has a head portion 24 which servesas a fixed electrical contact and it is seen that the rivets 22 alsohold the male terminal connectors 26 in place with respect to thehousing 10. The housing 10 is also formed with a post or projectiondesignated by reference numeral 28 which extends in the same directionas tubular extensions 20 of the housing. It is to be particularly notedthat the end 30 of the post 28 is not in the same vertical plane as thecontact 24 but is closer to the wall 32 of the housing than are the endsof the contacts 24. The contacts 24 are located at the same distancefrom the wall 32 of housing 10 and it can be seen that the contacts 24and post 28 are A diaphragm formed of a suitable elastomeric materialsuch as rubber is generally designated by reference numeral 34 and isprovided with a circumferentially extending portion 36 formed with anannular groove 38 that embraces the circumferentially extending flange12 of housing 10. The diaphragm carries an annular shaped metal contactplate 40 which has a central aperture embracing a projecting portion 42of the diaphgram. A spring 44 is interposed between the metal contactplate 40 and a projecting portion 46 of the housing 10. The spring 44normally holds the contact plate 40 in the position illustrated inFIGURE 2 and out of contact with the fixed contacts 24.

In operation of the switch illustrated in FIGURES 1 and 2, one of theintegrally formed tubes 16 or 18 is connected with a vacuum source whilethe other tube is connected with some other device that is adapted to beoperated by vacuum. The chamber defined by the diaphragm 34 and thehousing 10 thus forms a transfer chamber or junction for another vacuumoperated device. It, of course, will be appreciated by those skilled inthe are that one of the tubes need not be used since it is onlynecessary that the interior of the diaphragm 34 and housing 10 beconnected with vacuum to operate the switch.

When the chamber defined by the diaphragm and housing is connected withvacuum the diaphragm is pulled rightwardly in FIGURE 2 and the contactplate 40 first engages the contacts 24. As the diaphgram continues tomove rightwardly it will begin to tilt since it is only engaged bycontacts 24 and will come to its final position when the contact plate40 engages the end 30 of post 28. In this final closed position of theswitch the contact plate 40 will be tilted along a plane that includesthe ends of contacts 24 and the end 30 of post 28. This tilting actionis, of course, due to the fact that the contacts 24 are located closerto the plate 40 than is the end 30 of post 28 during the at restposition of contactor 40. It has been found that this tilting actioncauses a slight rotation of the metal contact plate 40 during eachclosure of the switch. This rotation tends to cause a wiping actionbetween the contact plate 40 and the contacts 24 and a diflferent partof the contact plate 40 is thus presented to the contacts 24 during eachclosure of the switch.

Referring now to FIGURES 3 and 4, a modified switch made in accordancewith this invention is illustrated. In this switch the case or housingis generally designated by reference numeral 50 and is once morepreferably located radially of the longitudinal axis of the housing aformed of a plastic moldable material such as nylon. The case or housing50 has a circurnterentially extending flange 52 that is fitted in agroove 54 formed in the diaph ragm 56. The diaphragm as in the previousswitch is formed of an elastomeric material such as rubber and has acentral projecting portion 53. The diaphragm carries a metal plate 60having an inner edge fitted within a groove 59 which in embodiment ofFIGURES 3 and 4 serves to lend rigidity to the diaphragm but does notserve to conduct current.

The housing 54) has openings which respectively receive rivets 62 and 64having heads 66 and 68. The rivets 62 and 64 serve to hold the maleterminal connectors 70 and 72 in place with respect to the housing 50.The housing 59 is formed with a tubular portion 74 which serves toconnect the interior of the housing with a vacuum source and has aplurality of outwardly flared projecting portions 76 which are adaptedto be received within an aperture in a mounting plate.

As can be seen from FIGURE 4, the housing 56 is A formed with a chamberor recess 78 located in alignment with the projecting portion 58 ofdiaphragm 56. The chamber is surrounded in two places by projectingportions 86 which extend above the ends of contacts 66 and 68. It is tobe observed that the edges of contacts 66 and 68 extend over the chamber78 and engage a metal cont-act plate 82. A spring 84 interposed betweenthe housing and the metal contact plate 82 urges the contact plate intoengagement with the edge portions of contacts 66 and 68 as clearlyapparent from FIGURE 4.

It will be apparent from an inspection of FIGURE 4 that the switch ofthis embodiment is a normally closed switch with the metal contact plate82 contacting portions of contacts 66 and 63. The spring 84 normallyurges the contactor 32. into engagement with the fixed contacts 66 and68 and also serves to move the diaphragm 56 leftwardly when no vacuum isapplied to the chamber defined by the housing 50 and diaphragm 56. Whenvacuum is applied to the interior of diaphragm 56 and housing 50, thediaphragm 56 is moved rightwardly in FIGURE 4 and the projecting portion58 moves the contactor 82 out of engagement with contacts 66 and 68. Ashas been noted hereinbefore, when vacuum is no longer applied to theinterior of the switch, the spring 84 moves the diaphragm 56 back to itsposition illustrated in FIGURE 4 and reconnects the contacts 66 and 68.

When vacuum is applied to the interior of the switch, the metal plate 60cannot connect the contacts 66 and 68 as it is stopped in its movementby the projecting portions 80 which are formed integral with the housing50. The plate 60 serves to lend rigidity to the diaphragm 56 but doesnot serve to conduct electrical current.

It is to be observed that in each embodiment of the switch, the switchis formed essentially of two parts, namely, a case or housing assemblyand a diaphragm that is assembled to the case or housing assembly bymerely snapping the flanged portion of the case or housing into thecircumferentially extending groove of the diaphragm. It is also to beobserved that in each embodiment of the invention, integral means areformed on the case or housing for connection with a vacuum source andintegral attaching means are provided for projection into an apertureformed in a mounting plate.

While the embodiment of the present invention as herein disclosedconstitutes a preferred form, it is to be understood that other formsmight be adopted.

What is claimed is as follows:

1. An electric switch comprising, a casing formed of electricalinsulating material, said casing having a circumferentially extendingflange, a diaphragm having a circumferentially extending slot receivingsaid flange and forming a chamber with said casing, 21 metal contactplate carried by and rotatable with respect to said diaphragm, a pair offixed contacts supported by said casing, a post integrally formed withsaid casing, said contacts and said A. post being spaced at differentdistances from said contact plate when said contact plate is at rest,and passage means in said casing for connecting said chamber with asource of vacuum, said post and said contacts causing said contactor totilt when it engages said contacts and the end of said post.

2. An electric switch comprising, a casing formed of electricalinsulating material, a diaphragm secured to said casing carrying a metalcontact plate, said casing and diaphragm forming a chamber that isadapted to be connected with a source of vacuum, and means including apair of electrical contacts forming three points of contact for a commonside of said contact plate when said contact plate is moved by saiddiaphragm under the influence of vacuum, at least one of the points ofcontact being spaced a greater distance from the at rest position ofsaid contact plate than another of said points.

3. An electric switch comprising, a casing formed of electricalinsulating material, a diaphragm secured to said casing and forming achamber therewith which is adapted to be connected to a source ofvacuum, said diaphragm having a central projection, an integral contactplate having a central opening receiving said projection and engagingsaid diaphragm, and means including a pair of electrical contactsforming three points of contact for engaging a common side of saidcontact plate when said diaphragm moves said contact plate in onedirection, at least one of said points being spaced a greater distancefrom the at rest position of said contact plate than another of saidpoints.

4. An electric switch comprising, a casing formed of electricalinsulating material, a diaphragm secured to said casing and forming achamber therewith which is adapted to be connected to a source ofvacuum, said diaphragm having an integral projection, a contact platehaving a central opening receiving said projection and engaging saiddiaphragm, means including a pair of electrical contacts forming threepoints of contact engaging a common side of said contact plate when saiddiaphragm moves said contact plate in one direction, at least one ofsaid points being spaced a greater distance from the at rest position ofsaid contact plate than another of said points, and a spring interposedbetween said casing and said contact plate for urging said Contact plateaway from said points of contact.

5. An electric switch comprising, a casing formed of electricalinsulating material, a di. phragm secured to said casing, a metalcontact plate rotatably secured to said diaphragm, said casing anddiaphragm forming a chamber that is adapted to be connected with asource of vacuum, and means including a pair of electrical contactsforming three points of contact for a common side of said contact platewhen said contact plate is moved by said diaphragm under the influenceof vacuum, at least one of the points of contact being spaced a greaterdistance from the at rest position of said contact plate than another ofsaid points.

6. An electric switch comprising, a casing formed of electricalinsulating material, a diaphragm secured to said casing having anintegral projection, a metal contact plate rotatably supported on saidprojection, said casing and diaphragm forming a chamber that is adaptedto be connected with a source of vacuum, and means including a pair ofelectrical contacts forming three points of contact for a common side ofsaid contact plate when said contact plate is moved by said diaphragmunder the infiuence of vacuum, at least one of the points of contactbeing spaced a greater distance from the at rest position of saidcontact plate than another of said points.

7. An electrical switch comprising, a casing, a diaphragm secured tosaid casing and forming therewith a chamber that is adapted to beconnected to a source of vacuum, a contact plate carried by saiddiaphragm, and means including a pair of electrical contacts formingthree points of contact that engage a common side of said 5 contactplate when said contact plate is moved by said diaphragm under theinfluence of vacuum, at least one of said points being spaced a greaterdistance from the at rest position of said contact plate than another ofsaid points.

References Cited in the file of this patent UNITED STATES PATENTS1,310,523 Eberhard July 22, 1919 6 May et a1. Sept. 2, 1924 White Aug.4, 1936 Cressey Apr. 13, 1948 Anger et a1. Mar. 9, 1954 Courtot Nov. 19,1957 FOREIGN PATENTS France Nov. 19, 1956

